Because what mathematics really is are the *proofs* not the solutions, not the algorithms, but that unbroken chain from a minimal set of assumptions to the solution.
Over and over we work to demonstrate this unbroken chain, though in most undergrad statistics courses this is just something we give up on in favor of getting the students competent enough with the algorithms to mostly apply them correctly. And that's part of why such courses aren't seen as "real math." 2/2